کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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6413829 | 1629964 | 2013 | 9 صفحه PDF | دانلود رایگان |
SummaryHigh suspended sediment (SPS) concentration exists in many Asian rivers. In addition, human activities and climate change can change river runoff, leading to the variation of SPS and pollutant concentrations. In this research, the effects of SPS and dissolved organic nitrogen (DON) concentration on DON transformation in river systems were studied through simulation experiments with samples collected from the Yellow River which is famous for its high SPS concentration. The results indicated that high DON concentration resulted in a longer retention time of NH4+-N and NO2--N in the system due to the inhibition effect of ammonia on nitrification. The re-suspension of sediment accelerated DON transformation, and both the ammonification and nitrification rates increased with SPS concentration. The ammonification rate constants obtained from the first-order kinetics were 0.286, 0.332, 0.538 dayâ1; the nitrification rate constants obtained from the Logistic model were 0.0018, 0.0038, 0.005 dayâ1 μmolâ1 Lâ1 for the systems with SPS concentration of 0, 5, 10 g Lâ1, respectively. Bacteria tended to attach onto SPS, and the specific growth rate in the systems with SPS was approximately two orders of magnitude higher than that without SPS in the first 3 days of cultivation, which resulted in an increase of DON transformation rate with SPS concentration. This study implied that DON transformation rate may be lower in the dry season than that in the wet season, and nitrogen transformation will be affected by the variation of river runoff and SPS concentration.
⺠Nitrification was inhibited by high dissolved organic nitrogen (DON) concentration. ⺠DON transformation rate increased with suspended sediment (SPS) concentration. ⺠Influence mechanism of DON concentration and SPS on DON transformation was studied. ⺠DON transformation rate may be lower in the dry season than that in the wet season. ⺠Nitrogen transformation in rivers was analyzed under the context of climate change.
Journal: Journal of Hydrology - Volume 484, 25 March 2013, Pages 96-104